William stewart



- w. STEWART.

Grinding Mm.

Patented Feb. 19, 1861.

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UNITED STATES PATENT OFFIE.

VILLIAM STIMVART, OF PHILADELPHIA, PENNSYLVANIA.

MILL.

Specification of Letters Patent No.

To all whom it may concern:

Be it known that I, IILLIAM STEWART, of Philadelphia., in the county ofPhiladelphia and State of Pennsylvania, have invented a new and usefulImprovement in Grinding- Mills; and I do hereby declare that the fo]lowing is a full, clear, and exact description of the saine, referencebeing had to the annexed drawings, making a part of this specification,in which- Figure 1 is a vertical central section of my invention takenin the line fc, Fig. 4. Fig. 2 is a detached external view of theconical grinder.l Fig. 3 is a detached veitical central section of theshell. Fig. 4 is a horizontal section of Fig. 1, taken in the line w,Fig. 1.

Similar letteis of reference indicate corresponding parts in the severalfigures.

The invention relates to an improvement in that class of grinding millsiii which a castemetal conical grinder is placed within a-shell ofcorresponding form. The chief difficulty attending the operation of thiskind of mill has been the producing of uneven work that is to say,portions of the article being ground, are discharged much coarser thanothers, and the mill while working rapidly produces ,inferior work. Inorder to obviate this difficulty diagonal teeth or projections have beenused in connectioii with the ordinary corrugations or grinding surfaces,said teeth or projections being designed to arrest the progress of thearticle being ground through the mill, and thereby insure its reductionto a proper fine state before its discharge. This arrangement has notbeen generally adopted as it creates as great a difficulty as the oneit` was designed to obviate, to wit, the choking or clogging of themill. This class of mills also have been hitherto liable to heat andsoon become worn and unfit for use.

My invention consists in a peculiar construction whereby the above nameddifficulties are avoided, while the advantages of this class of mills,to wit, rapidity of grinding in connection with economy of construction,are retained.

To enable those skilled in the art to vfully understand and construct myinvention I will proceed to describe it.

A represents a vertical shaft on which a frustum of a cone B, issecured, and C, C, C, C, 0, are rings or bands which are placed on B,one over the other, each ring 31,492, dated February 19, 1861.

or band being the frustuin of a cone, and the upper end of each a littlesmaller in diameter than the base of the one immediately above it, asshown clearly in Figs. l and 2. The rings or bands C, are of cast metal,while the conical body B, on which they are placed is of wood. The ringsor bands C, may be secured to their body B, in any proper vay so as toprevent them slipping or turning thereon and the whole number of ringswhen adjusted on their body B, may be described as being a frustum of acone with an unequal surface caused by the difference in the diametersof the adjoining surfaces of the rings or bands. By referring to Fig. 4it will be seen that the body B, on which the rings or bands C, are

placed is grooved longitudinally, and a projection a., on the inner sideof each ring or band is vfitted in this groove. This arrangementeffectually prevents the turning' of the rings or bands on the body B.The top ring or band C, is also secured to the body B, by screws o. Therings or bands C, are provided at their periphery with teeth orcoriugatioiis c, which are inclined from a vertical line in a greater orless degree according to the draft required, and the teeth of the ringsor bands gradually decrease in size from the upper to the lowermost ringor band, as shown clearly in Fig. 2.

D represents a conical shell which is of cast metal of suitablethickness and has a series of cast metal rings or bands E, E', E, E", E,secured within it. These rings or bands are of conical form, and whensecured one over the other in the shell D, form the frustuin of a hollowcone. The rings or bands E, are each provided with a projection c', attheir outer sides, and these projections fit in agroove (l, in the shellD,- see Fig. 4. This arrangement efectually prevents the rings or bandsE, from turning within the shell D. The lowermost ring or band E, restson horizontal pins or projections cZ, attached to the shell D.Tlie'inner surfaces of the rings or bands E, are pro vided with teeth orcorrugations c, which, like the teeth c, of the rings or bands C, areinclined from a vertical line in a. degree equal to the draft required.The inner surfaces of the rings or bands E, form a uniform surfacethroughout; that. is to say, the diameter of the adjoining ends of therings or bands are equal, as will be seen by referring to Figs. 1 and 3.

The rings or bands C, are placed within the rings or bands E, the shell.D, of the latter being secured permanently in a `vertical position, andthe lower edge of each ring or band C, just touches the lower edge ofits fellow ring or band E, as shown clearly in Fig. l, the rings orbands C, gradually receding from their fellows E, :troni their lower totheir upper ends. By this arrangement it will be seen that each ring orband C, with its fellow E, forms a distinct grinding device, and as theshaft A, and rings or bands C, rotate, the article to be ground passesconsecutively through a series of grinding devices which are toothed toact in the most eilicient way on the article at different stages of thegrinding process, and cause the same to be ground in a uniform manner. p

The superiority of my device over the ordinary conical grinder which iscast in one piece and is brought in contact with the shell only at itsbase, must be evident, for in this case many portions of the groundarticle escape in a coarse state. Besides the grinder being also cast inone piece, if it break or crack, an entire new casting is required, andthe same may also be said of the shell which is cast in one piece. In myinvention any of the rings or bands in case of breaking may be readilyreplaced by a new one. Y

I would remark that the rings or bands C, are provided at intervals withteeth or clearers a, which extend outward nearly to the teeth of therings or bands EA These prominent teeth are for the purpose ofpreventing the choking or clogging of the mill a result which iseffected in consequence of the clearers or teeth ai, stirring the massin the spaces between the upper parts of the rings or bands.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent, is

The construction of the grinder with a series of conical toothed ringsor concaves E, placed one above the other within an eXterior conicalcase D, and a series of conical grinding toot-hed rings C placed oneabove the other upon a cone B, the whole arranged and operating in themanner and for the purposes herein shown and described.

WILLIAM STEW'ART.

lVitnesses:

WILLIAM A. PALMER, JAMES MoCAI-IEN.

